0
extract
Sat 28th Dec 2013

Robot Rampage - thanks to Epic for sending in this fantastic picture of his Chistmas Scene with Poseable Robot. I've taken the liberty of adding slightly more fearsome face by the power of PhotoShop. Look out carol singers! He's behind you!

Thanks for sending the picture Epic!


Keep up to date: Receive the latest blog post by email

Rate this post:



This poseable robot is one of the paper projects I've produced for Brother's Creative Centre

It is now available to download for free on their website. Have fun!


The robot has a moveable head, poseable arms and poseable legs.


Bend his arms and legs and let him relax.

Or strike a balanced, robot dancer pose!


Keep up to date: Receive the latest blog post by email

Rate this post:



I'm still fiddling with the drive for the Clockwork Mouse and Flex-Robot projects. I'm aiming to create a drive which I can fit into a base box which I could then expand with other parts such as crank slider or cam if they were needed in future projects. Here is the latest mech that I have come up with. The handle is turned and the crank shaft drives the shaded area up and down.

It works really smoothly, there is nothing to catch or snag and I can add extra bits fairly easily if I choose to.


This unshaded close up gives you a better idea of what is going on inside the box. Plenty of room there for other mechanisms if needed.


The clockwork mouse model doesn't need any extra mechanisms so I've created this slimmed down version. I'll be putting this bare scotch yoke mech on the site tomorrow for you to play with. It must be mk iii or mk iv by now!


Keep up to date: Receive the latest blog post by email

Rate this post:



0
extract
Mon 16th Sep 2013

Time to link together the scotch yoke powered base, the legs and the arms. 

This animation shows one leg in action, obviously I'll be adding a second leg on the other side, I'll probably need to change the size of the leg parts as well to ensure the proportions of the finished model are good.

 


The arms seem to work well despite having only one tendon each to pull them upwards. Gravity handles the reverse trip just fine.
The next step is to join the body and legs together in a single unit. After which I need to spend a bit of time working on proportions of parts, for example, the body looks a bit over bulky.

 


As a side note I'm always happy to scavenge good ideas when I see them. I was sent a link to this free paper robot from an online insurance company. One thing I particularly liked was the repeating pattern used in the glue areas. I've recreated the effect here in the glue areas for the flex robot. Nice!


Keep up to date: Receive the latest blog post by email

Rate this post:



0
extract
Sun 15th Sep 2013

Experiments with tendon driven arms.

Two arms, connected to a body with tendons available to pull. I've used only a single tendon for each arm to pull the arm upwards. I'm relying on gravity to assist the return trip.


Pull both tendons at once to operate the arms.


Down...


...and up!

Next step is to link the body to a box via a bush rod then join the tendons to the box top so that the arms go up and down as the robot does.


Keep up to date: Receive the latest blog post by email

Rate this post:



1
extract
Fri 13th Sep 2013

Just time for a quick extra blog post...

This piece is intended as a matching flexible arm to go with the flexible legs.

The parts roll round quite nicely and glue together to make this flexible multi-part arm.

With the addition of a couple of long strips to act as tendons and a mighty claw we have a fully working robot arm!

The dimensions need a little tweaking but basically it works a treat!


Keep up to date: Receive the latest blog post by email

Rate this post:



0
extract
Fri 13th Sep 2013

Let's try something new. I'm working on the legs for the scotch robot. My original plan was to have a jointed two part leg but I thought, instead, that I'd have a go at a more flexible leg made up from short sections.


I put together six sections, each slightly smaller than the next.


Here's a simple experimental jig connected to the scotch yoke mechanism. The foot is fastened to the box top and the top of the leg connected by a flexible joint to the vertical drive shaft.


With the drive shaft in its lowest position the leg curves nicely then straightens out again as the drive shaft reaches its the highest position.


It should go together something like this.

It might be possible to construct the arms in a similar way and move them with a couple of paper 'tendons'. More experiments required. 


Keep up to date: Receive the latest blog post by email

Rate this post:



I've finished the scotch yoke part of the robot model. The sliding yoke fits nicely in the box. (See the previously post) I'll be publishing the base mechanism as separate project before continuing with the robot.


The drive handle and drive pin fit into a back plate on the box.


Everything fits together to complete the mechanism.


I've printed out parts onto coloured card and will be putting together them together in the morning.

-----

Oh, and I called in at Carvetii Coffee this afternoon...


Keep up to date: Receive the latest blog post by email

Rate this post:



1
extract
Sun 8th Sep 2013

The first draft of the upright scotch yoke mechanism has set off alarm bell.

Notice how the yoke is sloping down to the right. The parts are really hard to assemble and virtually impossible to keep square.


Combine that with the square section pillars and I start to think that I have moved away from proper paper engineering techniques. Square section pillars deform easily, not ideal for structural parts. And joining them together using a cut out slot in the base? Well, there is simply no excuse.


On putting together a measured out version of the vertical sliders and yoke I had the same problem of alignment with a pronounced tapering of the vertical shafts. These parts were so out of line that the model simply wouldn't fit together.


I've probably said this before but: It reminds me of Ironbridge. The very first bridge constructed from iron. The artisans who constructed this marvel, which stands to this day, were carpenters and stone masons. Iron was a new material to them. To join the bridge parts together they used the techniques they were familiar with. In this case, dovetail joints and dowels. 


It worked and is a truly beautiful structure but later constructions used techniques more suited to their materials.


With this allegory in mind I set off to redesign the scotch yoke mechanism using techniques more suited to paper engineering. Starting with the slot that makes up the yoke. I've redesigned it using triangular tube sections and also substantially reduced the width of the vertical shaft, down to six millimeters from eleven.


To replace the square section tubes and the slider tubes I've used a couple more triangles. These make a triangle shaped cut out which will locate accurately over a long triangle section tube.


A long triangle section slide can then easily be fitted to the inside wall of a box, one on each side ready to hold the yoke in place. The circular drive pin, which I've drawn in below, will move the yoke up and down. It's all looking promising but it is getting late. Full assembly tomorrow morning.


I made this sketch of my initial plans for this design. It has developed a fair bit from this point. That's usually the way once I start actually cutting stuff out.


Keep up to date: Receive the latest blog post by email

Rate this post:



You may remember the original scotch yoke mechanism. (Click the image to visit the post) In this model the rotating disk at the back of the model moved the sliding yoke side to side.
I wanted to use this mech in my forthcoming exercising robot idea. My plan was to rotate the yoke by ninety degrees and use one of the drive pins to move the robot up and down. The problem was that the long drive shafts on either side of the yoke would have made the box that the robot stood on incredibly tall.
 

Here's my proposed solution. Rather than a drive shaft at each end of the yoke I've opted for a main drive shaft then a couple of side shafts to keep everything lined up. This keeps everything nice and compact but should work just as well as the original design. 


I've slightly simplified the design of the rotating drive pin by getting rid of the rotating disk and replacing it with a pin in a bar connected to the main drive shaft and handle.

 


By changing the distance the drive pin is from the rotating drive shaft I can control how much the character on top of the box moves up and down.

 

 


And to satisfy your curiosity, here's an eight frame stop motion animation of the mechanism in action. Notice the two vertical guide shafts on either side are moving all over the place - this is because I had only pushed them into place but didn't glue them just incase I wanted to take the model apart and make changes. The finished design will be much more sturdy!

Apart from the slight wobbles, looking good I think! 

 


The original sketch from my note showing the winding key in place. 
Originally posted on Instagram


Keep up to date: Receive the latest blog post by email

Rate this post: